1. Technical Field
This application pertains to heating, ventilating and air conditioning systems and processes generally, and, more particularly, to energy efficiency in heating, ventilating and air conditioning systems and air handling processes for clean rooms and other environmentally controlled spaces that require large air change rates.
2. Description of Related Art
In air handling systems applicable to cleanrooms and other applications requiring large air exchange rates, the air is cooled to meet the sensible heat load of the cleanroom. If the cleanroom or other enclosed environment is to have relative humidity (RH) control in addition to a large air exchange rate, and if dehumidification is achieved by cooling, then the air is cooled to a dew point corresponding to the required moisture content level by allowing the excess moisture to condense on the cooling coils of the air conditioning system. Typically, this means that the air leaving the cooling coil would be too cold for the cleanroom environment. In other words, in such a dehumidification system, the air has been cooled to a temperature that is in excess of the sensible heat load of the environmentally controlled space. Therefore, the air leaving the cooling coil must be re-heated to the required temperature. If however, dehumidification is achieved by adsorptive processes, the air is heated due to heat of adsorption and must then be cooled down to meet the sensible heat load of the cleanroom. Other systems, such as the damper system of Martin Gagnon, et alii, in the Air Handling Systems Or Devices Intermingling Fresh And Stale Air assigned Ser. No. 10/903010 and filed in the U.S. Patent & Trademark Office on the 2nd of Aug. 2004, Pub. No. 2005/0000681 dated on the 6th of Jan. 2005, exhaust a portion of the stale air from the enclosure to create a reduced stale air stream, and create a mixed or intermingled air stream by introducing an amount of fresh air into the reduced stale air stream.
I have found that both the cooling of the air to a dew point corresponding to the required moisture content level followed by reheating in dehumidification processes, as well as the heating of the air to achieve adsorption followed by cooling of the air in an adsorption process, are inefficient and unnecessarily expensive in terms of the energy consumed. Although a by pass of airflow may occur around the air conditioning unit of an air handling unit in these processes, the by pass is incidental and no process has been able to optimize energy savings and minimize or eliminate reheating by harnessing a by pass of air flow during the air handling process.